@property (weak, nonatomic) IBOutlet UIPickerView *myPickerView;
@property (strong, readwrite, nonatomic) NSMutableArray *userAccounts;


-(void)authenticateUser
{
    [self populateDataSourceWithResultBlock:^(NSArray *accounts, NSError *error)
     {
                 [self.twitterAccountPickerView reloadAllComponents];
     }];
}

- (void)populateDataSourceWithResultBlock:(void (^)(NSArray *accounts, NSError *error))resultBlock
{
    self.userAccounts = [[NSMutableArray alloc] initWithObjects:@"one", @"two",nil];

    dispatch_sync(dispatch_get_main_queue(), ^{
        resultBlock(self.userAccounts, error);
    });
}


#pragma mark - UIPickerViewDataSource

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 1;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    return self.userAccounts.count;
}

#pragma mark - UIPickerViewDelegate

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:   (NSInteger)component
{
    ACAccount *account = (ACAccount *)self.userAccounts[row];
    NSString *username = [NSString stringWithFormat:@"@%@", account.username];
    return username;
}